Generation methods isoxazoline compounds

As discussed in Section 6.2, nitro compounds are good precursors of nitrile oxides, which are important dipoles in cycloadditions. The 1,3-dipolar cycloaddition of nitrile oxides with alkenes or alkynes provides a straightforward access to 2-isoxazolines or isoxazoles, respectively. A number of ring-cleaving procedures are applicable, such that various types of compounds may be obtained from the primary adducts (Scheme 8.18). There are many reports on synthetic applications of this reaction. The methods for generation of nitrile oxides and their reactions are discussed in Section 6.2. Recent synthetic applications and asymmetric synthesis using 1,3-dipolar cycloaddition of nitrile oxides are summarized in this section. 

Cyclization is known to release resin-bound compounds without a linker. Hydantoin ring formation releases resin-bound compounds smoothly, producing interesting hydantoin derivatives with potential medicinal or biological activity. Resin-bound alkenes reacted with nitrile oxides that were generated with Mukaiyama s method from nitroalkane (Scheme 11.48). The isoxazolines were cleaved from the resin via ahydantoin formation upon heating under basic conditions. 

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